The present invention relates to an entrance system having a 180.degree. image angle which is made of light-transmitting material and intended for use in radiation detectors for differing wavelength ranges of sunlight. The invention also relates to a radiation detector provided with such a system.
Radiation detectors for differing wavelength ranges of sunlight are commercially available, such as, for example, a device supplied by Eppley Laboratories. In this device an arrangement of photodiode, interference filter and diaphragm is closed off by a planar diffusing screen. Such a device can be used for investigations of the chemistry of the air only to a limited extent, on account of its directionality.
Arrangements having a "fisheye objective" are accordingly already known, which arrangements have an image angle of 160.degree.. These devices do indeed receive light from all sides up to an image angle of 160.degree., but their sensitivity is not uniform. Furthermore, such objectives are available only to a limited extent, and there are, in particular, problems concerning the range of ultraviolet light, for which quartz glass objectives are required.